The NYSCF First Annual Translational Stem Cell Research Conference
Posted February 28, 2007
Founded in 2005, the New York Stem Cell Foundation (NYSCF) is a privately-funded foundation supporting human embryonic stem cell research in the search for cures of major diseases. When the NYSCF held its first Translational Research Conference on October 23–24, 2006, at the Rockefeller University, the first talks provided an update on the current legal landscape of stem cell science.
For leading stem cell researchers—many of whom assembled at this historic conference—the focus was scientific rather than political. The recurring theme of the day-long conference was, exactly what do we know about stem cells, and what can we do with them? Scientists from around the world discussed the most recent findings in the most promising research areas: somatic cell nuclear transfer (SCNT), diabetes, heart disease, cancer, and neurology.
This symposium and eBriefing were made possible with support from:
The New York Stem Cell Foundation
The sponsor of the First Translational Stem Cell Research Conference is a nonprofit organization organized to support scientists engaged in stem cell research, to educate the public about the importance and potential benefits of the field, and to establish research facilities supported by private funding. They are planning their second annual conference for October 15-16, 2007.
Beta Cell Biology Consortium
An interdisciplinary team of researchers working to advance our understanding of pancreatic islet development and function with the long-term goal of developing a cell-based therapy for insulin delivery.
California Institute for Regenerative Medicine
Governed by the Independent Citizens Oversight Committee, CIRM was established in 2004 with the passage of Proposition 71, the California Stem Cell Research and Cures Initiative. The statewide ballot measure, which provided $3 billion in funding for stem cell research at California universities and research institutions, was approved by California voters, and called for the establishment of an entity to make grants and provide loans for stem cell research, research facilities, and other vital research opportunities.
European Consortium for Stem Cell Research
EuroStemCell, is an Integrated Project of the European Union's Sixth Framework Programme. The goal of the 4-year project is to develop an advanced technological platform for new cell based therapies and create a foundation for translational research in the stem cell field. The project draws together the capabilities of 11 academic centres and 3 SMEs in 8 European countries, with expertise encompassing transgenesis, stem cell biology, developmental biology, tissue repair, in vivo disease models and clinical cell transplantation. The key aim is to develop well-characterized cell lines of therapeutic potential derived from stem cells of embryonic, neural, mesodermal and epithelial origin.
International Society for Stem Cell Research
From a society promoting the exchange of information on stem cell research, this site provides a wide variety of resources, including a glossary of terms, a list of relevant meetings, and information for the general public. Includes a listing of human embryonic stem cell lines, with links and protocols.
International Stem Cell Forum (ISCF)
The ISCF is made up of 14 funders of stem cell research from around the world. It was founded in January 2003 to encourage international collaboration and funding support for stem cell research.
Juvenile Diabetes Research Foundation
JDRF is the leading charitable funder and advocate of type 1 (juvenile) diabetes research worldwide. The mission of JDRF is to find a cure for diabetes and its complications through the support of research. Their site contains information about stem cell research for treating diabetes.
The Stem Cell Database
A joint project of the laboratories of Ihor R. Lemischka and Kateri A. Moore (Princeton University) and Christian Stoeckert (University of Pennsylvania), this site serves as a catalog of the genes involved in blood cell production originating from multipotent, self-renewing hematopoietic stem cells.
Eggan K, Baldwin K, Tackett M, et al. 2004. Mice cloned from olfactory sensory neurons. Nature 428: 44-49.
Eggan K, Jaenisch R. 2003. Micromanipulating dosage compensation: understanding X-chromosome inactivation through nuclear transplantation. Semin. Cell Dev. Biol. 14: 349-358.
Eggan K, Jurga S, Gosden R. 2006. Ovulated oocytes in adult mice derive from non-circulating germ cells. Nature 441: 1109-1114.
Geijsen N, Horoschak M, Kim K, et al. 2004. Derivation of embryonic germ cells and male gametes from embryonic stem cells. Nature 427: 148-154.
Jaenisch R, Hochedlinger K, Blelloch R et al. 2004. Nuclear cloning, epigenetic reprogramming, and cellular differentiation. Cold Spring Harb. Symp. Quant. Biol. 69: 19-27.
Takahashi K, Yamanaka S. 2006. Induction of pluripotent stem cells from mouse embryonic and adult fibroblast cultures by defined factors. Cell 126: 663-676.
Renee Reijo Pera
Ezeh UI, Turek PJ, Reijo RA, Clark AT. 2005. Human embryonic stem cell genes OCT4, NANOG, STELLAR, and GDF3 are expressed in both seminoma and breast carcinoma. Cancer 104: 2255-2265.
Kostiner DR, Turek, PJ, Reijo RA.1998. Male infertility: analysis of the markers and genes on the human Y chromosome. Hum. Reprod. 13: 3032-3038. (PDF, 119 KB) Full Text
Looijenga LH, Hermus R, Gillis AJ, et al. 2006. Genomic and expression profiling of human spermatocytic seminomas: primary spermatocyte as tumorigenic precursor and DMRT1 as candidate chromosome 9 gene. Cancer Res. 66: 290-302. Full Text
Mulhall JP, Reijo R, Alagappan R, et al. 1997. Azoospermic men with deletion of the DAZ gene cluster are capable of completing spermatogenesis: fertilization, normal embryonic development and pregnancy occur when retrieved testicular spermatozoa are used for intracytoplasmic sperm injection. Hum. Reprod. 12: 503-508. (PDF, 148 KB) Full Text
Nudell D, Castillo M, Turek PJ, Pera RR. 2000. Increased frequency of mutations in DNA from infertile men with meiotic arrest. Hum. Reprod. 15: 1289-1294. Full Text
Reijo RA, Dorfman DM, Slee R, et al. 2000. DAZ family proteins exist throughout male germ cell development and transit from nucleus to cytoplasm at meiosis in humans and mice. Biol. Reprod. 63: 1490-1496. Full Text
Saxena R, Brown LG, Hawkins T, et al. 1996. The DAZ gene cluster on the human Y chromosome arose from an autosomal gene that was transposed, repeatedly amplified and pruned. Nat. Genet. 14: 292-299.
Amit M, Itskovitz-Eldor J. 2006. Sources, derivation, and culture of human embryonic stem cells. Semin. Reprod. Med. 24: 298-303.
James D, Noggle SA, Swigut T, Brivanlou AH. 2006. Contribution of human embryonic stem cells to mouse blastocysts. Dev. Biol. 295: 90-102.
Levine AJ, Brivanlou AH. 2006. GDF3, a BMP inhibitor, regulates cell fate in stem cells and early embryos. Development 133: 209-216. Full Text
Noggle SA, James D, Brivanlou AH. 2005. A molecular basis for human embryonic stem cell pluripotency. Stem Cell Rev. 1: 111-118.
Sato N, Brivanlou AH. 2006. Manipulation of self-renewal in human embryonic stem cells through a novel pharmacological GSK-3 inhibitor. Methods Mol. Biol. 331: 115-128.
Sato N, Brivanlou AH. 2006. Microarray approach to identify the signaling network responsible for self-renewal of human embryonic stem cells. Methods Mol. Biol. 331: 267-283.
Sato N, Meijer L, Skaltsounis L, et al. 2004. Maintenance of pluripotency in human and mouse embryonic stem cells through activation of Wnt signaling by a pharmacological GSK-3-specific inhibitor. Nat. Med. 10: 55-63.
Spagnoli FM, Brivanlou AH. 2005. A full menu for stem-cell research. Genome Biol. 6: 311.
Campbell KH, McWhir J, Ritchie WA, Wilmut I. 1996. Sheep cloned by nuclear transfer from a cultured cell line. Nature 380: 64-66.
Choudhary M, Nesbitt M, Leary C, Murdoch AP. 2006. Donation of fresh oocytes for nuclear transfer research—a new approach. Reprod. Biomed. Online 13: 301-302.
Hall VJ, Compton D, Stojkovic P, et al. 2007. Developmental competence of human in vitro aged oocytes as host cells for nuclear transfer. Hum. Reprod. 22: 52-62.
Herbert M, Levasseur M, Homer H, et al. 2003. Homologue disjunction in mouse oocytes requires proteolysis of securin and cyclin B1. Nat. Cell Biol. 5: 1023-1025.
Lavoir MC, Weier J, Conaghan J, Pedersen RA. 2005. Poor development of human nuclear transfer embryos using failed fertilized oocytes. Reprod. Biomed. Online 11: 740-744.
Ozil JP, Huneau D. 2001. Activation of rabbit oocytes: the impact of the Ca2+ signal regime on development. Development 128: 917-928. (PDF, 310 KB) Full Text
Stojkovic M, Stojkovic P, Leary C, et al. 2005. Derivation of a human blastocyst after heterologous nuclear transfer to donated oocytes. Reprod. Biomed. Online 11: 226-231.
Gadue P, Huber TL, Paddison PJ, Keller GM. 2006. Wnt and TGF-beta signaling are required for the induction of an in vitro model of primitive streak formation using embryonic stem cells. Proc. Nat. Acad. Sci. USA 103: 16806-16811.
Germano IM, Uzzaman M, Beneviste RJ, et al. 2006. Apoptosis in human glioblastoma cells produced using embryonic stem cell-derived astrocytes expressing tumor necrosis factor-related apoptosis-inducing ligand. J. Neurosurg. 105: 88-95.
Gouon-Evans, Boussemart L, Gadue P, et al. 2006. BMP-4 is required for hepatic specification of mouse embryonic stem cell-derived definitive endoderm. Nat. Biotechnol. 24: 1402-1411.
Kattman SJ, Huber TL, Keller GM. 2006. Multipotent flk-1+ cardiovascular progenitor cells give rise to the cardiomyocyte, endothelial, and vascular smooth muscle lineages. Dev. Cell 11: 723-732.
Kennedy M, D'Souza SL, Lynch-Kattman M, et al. 2006. Development of the hemangioblast defines the onset of hematopoiesis in human ES cell differentiation cultures. Blood Dec. 5; [Epub ahead of print]
Zafonte BT, Liu S, Lynch-Kattman M, et al. 2007. Smad1 expands the hemangioblast population within a limited developmental window. Blood 109: 516-523.
Buteau J, Shlien A, Foisy S, Accili D. 2007. Metabolic diapause in pancreatic beta-cells expressing a gain-of-function mutant of the forkhead protein Foxo1. J. Biol. Chem. 282: 287-293.
Buteau J, Spatz ML, Accili D. 2006. Transcription factor FoxO1 mediates glucagon-like peptide-1 effects on pancreatic beta-cell mass. Diabetes 55: 1190-1196. Full Text
Matsumoto M, Han S, Kitamura T, Accili D. 2006. Dual role of transcription factor FoxO1 in controlling hepatic insulin sensitivity and lipid metabolism. J. Clin. Invest. 116: 2464-2472. Full Text
Okamoto H, Hribal ML, Lin HV, et al. 2006. Role of the forkhead protein FoxO1 in beta cell compensation to insulin resistance. J. Clin. Invest. 116: 775-782. Full Text
Allen M. Spiegel
Schnepp RW, Chen YX, Wang H. 2006. Mutation of tumor suppressor gene Men1 acutely enhances proliferation of pancreatic islet cells. Cancer Res. 66: 5707-5715.
Tayaramma T, Ma B, Rhode M, Mayer H. 2006. Chromatin-remodeling factors allow differentiation of bone marrow cells into insulin-producing cells. Stem Cells 24: 2858-2867.
Xu X, Kahan B, Forgianni A, et al. 2006. Endoderm and pancreatic islet lineage differentiation from human embryonic stem cells. Cloning Stem Cells 8: 96-107.
Zalzman M, Anker-Kitai L, Efrat S. 2005. Differentiation of human liver-derived, insulin-producing cells toward the β-cell phenotype. Diabetes 54: 2568-2575. Full Text
De Coppi P, Bartsch G Jr, Siddiqui MM, et al. 2007. Isolation of amniotic stem cell lines with potential for therapy. Nat. Biotechnol. 25: 100-106.
De Coppi P, Callegari A, Chiavegato A, et al. 2007. Amniotic fluid and bone marrow derived mesenchymal stem cells can be converted to smooth muscle cells in the cryo-injured rat bladder and prevent compensatory hypertrophy of surviving smooth muscle cells. J. Urol. 177: 369-376.
Delo DM, DeCoppi P, Bartsch, G Jr, Atala A. 2006. Amniotic fluid and placental stem cells. Methods Enzymol. 419: 426-438.
Eberli D, Atala A. 2006. Tissue engineering using adult stem cells. Methods Enzymol. 420: 287-302.
Hipp J, Atala A. 2006. GeneChips in stem cell research. Methods Enzymol. 420: 162-224.
Yu Y, Fuhr J, Boye E, et al. 2006. Mesenchymal stem cells and adipogenesis in hemangioma involution. Stem Cells 24: 1605-1612.
Boyer LA, Lee TI, Cole MF, et al. 2005. Core transcriptional regulatory circuitry in human embryonic stem cells. Cell 122: 947-956.
Cowan CA, Atienza J, Melton DA, Eggan K. 2005. Nuclear reprogramming of somatic cells after fusion with human embryonic stem cells. Science 309: 1369-1373.
Dor Y, Brown J, Martinez OI, Melton DA. 2004. Adult pancreatic beta-cells are formed by self-duplication rather than stem-cell differentiation. Nature 429:41-46.
Greenwood AL, Li S, Jones K, Melton DA. 2007. Notch signaling reveals developmental plasticity of Pax4+ pancreatic endocrine progenitors and shunts them to a duct fate. Mech. Dev. 124: 97-107.
Lee TI, Jenner RG, Boyer LA, et al. 2006. Control of developmental regulators by Polycomb in human embryonic stem cells. Cell 125: 301-313.
Melton DA. 2006. Reversal of type 1 diabetes in mice. N. Engl. J. Med. 355: 89-90.
Nikolova G, Jabs N, Konstantinova I, et al. 2006. The vascular basement membrane: a niche for insulin gene expression and Beta cell proliferation. Dev. Cell 10: 397-405.
Murtaugh LC, Law AC, Dor Y, Melton DA. 2005. Beta-catenin is essential for pancreatic acinar but not islet development. Development 132: 4663-4674.
Shaywitz DA, Melton DA. 2005. The molecular biography of the cell. Cell 120: 729-731.
Stanger BZ, Datar R, Murtaugh LC, Melton DA. 2005. Direct regulation of intestinal fate by Notch. Proc. Natl. Acad. Sci. USA 102: 12443-12448. Full Text
Stanger BZ, Stiles B, Lauwers GY, et al. 2005. Pten constrains centroacinar cell expansion and malignant transformation in the pancreas. Cancer Cell 8: 185-195.
Stanger BZ, Tanaka AJ, Melton DA. 2007. Organ size is limited by the number of embryonic progenitor cells in the pancreas but not the liver. Nature Jan 28; [Epub ahead of print]
Faden RR, Dawson L, Bateman-House AS, et al. 2003. Public stem cell banks: considerations of justice in stem cell research and therapy. Hastings Cent. Rep. 33: 13-27.
Frimberger D, Morales N, Gearhart JD, et al. 2006. Human embryoid body-derived stem cells in tissue engineering-enhanced migration in co-culture with bladder smooth muscle and urothelium. Urology 67: 1298-1303.
Jansen JF, Shamblott MJ, van Zijl PC, et al. 2006. Stem cell profiling by nuclear magnetic resonance spectroscopy. Magn. Reson. Med. 56: 666-670.
Kerr CL, Shamblott MJ, Gearhart JD. 2006. Pluripotent stem cells from germ cells. Methods Enzymol. 419: 400-426.
Kerr CL, Gearhart JD, Elliott AM, Donovan PJ. 2006. Embryonic germ cells: when germ cells become stem cells. Semin. Reprod. Med. 24: 304-313.
Mueller D, Shamblott MJ, Fox HE, et al. 2005. Transplanted human embryonic germ cell-derived neural stem cells replace neurons and oligodendrocytes in the forebrain of neonatal mice with excitotoxic brain damage. J. Neurosci. Res. 82: 592-608.
Sterneckert JL, Hill CM, Palmer R, Gearhart JD. 2005. Bone morphogenetic proteins produced by cells within embryoid bodies inhibit ventral directed differentiation by Sonic Hedgehog. Cloning Stem Cells 7: 27-34.
Wilmut I, West MD, Lanza RP, et al. 2005. Human embryonic stem cells. Science 310: 1903.
Sherman W, Martens TP, Viles-Gonzalez JF, Siminiak T. 2006. Catherter-based delivery of cells to the heart. Nat. Clin. Pract. Cardiovasc. Med. 3 Suppl. 1: S57-S64.
Amit N. Patel
Adusumilli PS, Tuorto S, Patel AN. 2006. Stem cells: science and society. Natl. Med. J. India. 19: 47-48.
Patel AN, Geffner L, Vina RF, et al. 2005. Surgical treatment for congestive heart failure with autologous adult stem cell transplantation: a prospective randomized study. J. Thorac. Cardiovasc. Surg. 130: 1631-1638.
Shepler SA, Patel AN. 2007. Cardiac cell therapy: a treatment option for cardiomyopathy. Crit. Care Nurs. Q. 30: 74-80.
Cai C-L, Liang X, Shi Y, et al. 2003. Isl1 identifies a cardiac progenitor population that proliferates prior to differentiation and contributes a majority of cells to the heart. Dev. Cell 5: 877-889.
Chien KR, 2006. Making a play at regrowing hearts. The Scientist (August). Full Text
Laugwitz K-L, Moretti A, Lam J, et al., 2005. Postnatal isl1+ cardioblasts enter fully differentiated cardiomyocyte lineages. Nature 433: 647-653.
Chien KR, Karsenty G. 2005. Longevity and lineages: toward the integrative biology of degenerative diseases in heart, muscle, and bone. Cell 120: 533-544.
Moretti A, Caron L, Nakano A, et al. 2006. Multipotent embryonic isl1+ progenitor cells lead to cardiac, smooth muscle, and endothelial cell diversification. Cell 127: 1151-1165.
Bernardi R, Guernah I, Grisendi S, et al. 2006. PML inhibits HIF-1α translation and neoangiogenesis through repression of mTOR. Nature 442: 779-785.
Jin DK, Shido K, Kopp HG, et al. 2006. Cytokine-mediated deployment of SDF-1 induces revascularization through recruitment of CXCR4+ hemangiocytes. Nat. Med. 12: 557-567.
Kaplan RN, Riba RD, Zacharoulis S, et al. 2005. VEGFR1-positive haematopoietic bone marrow progenitors initiate the pre-metastatic niche. Nature 438: 820-827.
Kopp HG, Hooper AT, Broekman MJ, et al. 2006. Thrombospondins deployed by thrombopoietic cells determine angiogenic switch and extent of revascularization. J. Clin. Invest. 116: 3277-3291. Full Text
Ruan J, Hyjek E, Kermani P, et al. 2006. Magnitude of stromal hemangiogenesis correlates with histologic subtype of non-Hodgkin's lymphoma. Clin. Cancer Res. 12: 5622-5631.
Hochedlinger K, Jaenisch R. 2006. Nuclear reprogramming and pluripotency. Nature 441: 1061-1067.
Hochedlinger K, Yamada Y, Beard C, Jaenisch R. 2005. Ectopic expression of Oct-4 blocks progenitor-cell differentiation and causes dysplasia in epithelial tissues. Cell 121: 465-477.
Jaenisch R, Hochedlinger K, Eggan K. 2005. Nuclear cloning, epigenetic reprogramming, and cellular differentiation. Novartis Found. Symp. 265: 107-118.
Takahashi K, Yamanaka S. 2006. Induction of pluripotent stem cells from mouse embryonic and adult fibroblast cultures by defined factors. Cell 126: 663-676.
Blanpain C, Lowry WE, Geoghegan A, et al. 2004. Self-renewal, multipotency, and the existence of two cell populations with an epithelial stem cell niche. Cell 118: 635-648. Full Text
Blanpain C, Lowry WE, Pasolli HA, Fuchs E. 2006. Canonical notch signaling functions as a commitment switch in the epidermal lineage. Genes Dev. 20: 3022-3035.
Lechler T, Fuchs E. 2005. Asymmetric cell divisions promote stratification and differentiation of mammalian skin. Nature 437: 275-280. Full Text
Lowry WE, Blanpain C, Nowak JA, et al. 2005. Defining the impact of beta-catenin/Tcf transactivation on epithelial stem cells. Genes Dev. 19: 1596-1611. Full Text
Morris RJ, Liu Y, Marles L, et al. 2004. Capturing and profiling adult hair follicle stem cells. Nat. Biotechnol. 22: 411-417.
Nguyen H, Rendl M, Fuchs E. 2006. Tcf3 governs stem cell features and represses cell fate determination in skin. Cell 127: 171-183.
Rhee H, Polak L, Fuchs E. 2006. Lhx2 maintains stem cell character in hair follicles. Science 312: 1946-1949.
Tumbar T, Guasch G, Greco V, et al. 2004. Defining the epithelial stem cell niche in skin. Science 303: 359-363.
Ban J, Bonifazi P, Pinato G, et al. 2006. ES-derived neurons form functional networks in vitro. Stem Cells Nov 16; [Epub ahead of print]
Barberi T, Studer L. 2006. Mesenchymal cells. Methods Enzymol. 418: 194-208.
Barberi T, Willis LM, Socci ND, Studer L. 2005. Derivation of multipotent mesenchymal precursors from human embryonic stem cells. PLoS Med. 2: e161. Full Text
Ferrari D, Sanchez-Pernaute R, Lee H, et al. 2006. Transplanted dopamine neurons derived from primate ES cells preferentially innervate DARPP-32 striatal progenitors within the graft. Eur. J. Neurosci. 24: 1885-1896.
Sanchez-Pernaute R, Studer L, Ferrari D, et al. 2005. Long-term survival of dopamine neurons derived from parthenogenetic primate embryonic stem cells (cyno-1) after transplantation. Stem Cells 23: 914-922. Full Text
Tabar V, Panagiotakos G, Greenberg ED, et al. 2005. Migration and differentiation of neural precursors derived from human embryonic stem cells in the rat brain. Nat. Biotechnol. 23: 601-606.
Tomishima MJ, Hadjantonakis AK, Gong S, Studer L. 2007. Production of Green Fluorescent Protein Transgenic Embryonic Stem Cells Using the GENSAT Bacterial Artificial Chromosome Library. Stem Cells 25: 39-45.
Dasen JS, Tice BC, Brenner-Morton S, Jessell TM. 2005. A Hox regulatory network establishes motor neuron pool identity and target-muscle connectivity. Cell 123: 477-491.
Liem KF Jr, Tremml G, Jessell T. 1997. A role for the roof plate and its resident TGFβ-related proteins in neuronal patterning in the dorsal spinal cord. Cell 91: 127-138. Full Text
Liu JP, Laufer E, Jessell T. 2001. Assigning the positional identity of spinal motor neurons: rostrocaudal patterning of Hox-c expression by FGFs, Gdf11, and retinoids. Neuron 32: 997-1012.
Roelink H, Augsburger A, Heemskerk J, et al. 1994. Floor plate and motor neuron induction by vhh-1, a vertebrate homolog of hedgehog expressed by the notochord. Cell 76: 761-775. Full Text
Barkho BZ, Song H, Aimone JB, et cl. 2006. Identification of astrocyte-expressed factors that modulate neural stem/progenitor cell differentiation. Stem Cells Dev. 15: 407-421.
Lie DC, Colamarino SA, Song HJ, et al. 2005. Wnt signalling regulates adult hippocampal neurogenesis. Nature 437: 1370-1375.
Ming GL, Song H. 2005. Adult neurogenesis in the mammalian central nervous system. Annu. Rev. Neurosci. 28: 223-250.
Owens DF, Kriegstein AR. 2002. Is there more to GABA than synaptic inhibition? Nat. Rev. Neurosci. 3: 715-727.
Song HJ, Stevens CF, Gage FH. 2002. Neural stem cells from adult hippocampus develop essential properties of functional CNS neurons. Nat. Neurosci. 5: 438-445.
Kriegstein AR. 2005. Constructing circuits: neurogenesis and migration in the developing neocortex. Epilepsia 46 Suppl. 7: 15-21.
Kriegstein A, Noctor S, Martinez-Cerdeno V. 2006. Patterns of neural stem and progenitor cell division may underlie evolutionary cortical expansion. Nat. Rev. Neurosci. 7: 883-990.
Kriegstein AR, Noctor SC. 2004. Patterns of neuronal migration in the embryonic cortex. Trends Neurosci. 27: 392-399.
Martinez-Cerdeno V, Noctor SC, Kriegstein AR. 2006. The role of intermediate progenitor cells in the evolutionary expansion of the cerebral cortex. Cereb. Cortex 16 Suppl. 1: 52-61.
Somatic Cell Nuclear Transfer
Harold Varmus, MD
Harold Varmus, former director of the National Institutes of Health and co-recipient of a Nobel Prize for studies of the genetic basis of cancer, has served as the president and chief executive officer of Memorial Sloan-Kettering Cancer Center in New York City since January 2000.
Much of Varmus's scientific work was conducted during 23 years as a faculty member at the University of California, San Francisco, Medical School, where he and J. Michael Bishop and their coworkers demonstrated the cellular origins of the oncogene of a chicken retrovirus. This discovery led to the isolation of many cellular genes that normally control growth and development and are frequently mutated in human cancer. For this work, Bishop and Varmus received many awards, including the 1989 Nobel Prize for Physiology or Medicine. Varmus is also widely recognized for his studies of the replication cycles of retroviruses and hepatitis B viruses, the functions of genes implicated in cancer, and the development of mouse models of human cancer (the focus of much of the current work in his laboratory at Memorial Sloan-Kettering Cancer Center).
Varmus has authored over 300 scientific papers and four books, including an introduction to the genetic basis of cancer for a general audience, and he has been an advisor to the federal government, pharmaceutical and biotechnology firms, and many academic institutions. He served on the World Health Organization's Commission on Macroeconomics and Health from 2000 to 2002; is a co-founder and chairman of the board of directors of the Public Library of Science, a publisher of open access journals in the biomedical sciences; chairs the scientific board of the Grand Challenges in Global Health at the Bill and Melinda Gates Foundation; and is involved in initiatives to promote science in developing countries, including the Global Science Corps, through the Science Initiatives Group. He has been a member of the U.S. National Academy of Sciences since 1984 and of the Institute of Medicine since 1991, and has received the National Medal of Science, the Vannevar Bush Award, and several honorary degrees and other prizes, in addition to the Nobel Prize.
Diabetes and Autoimmune Disease
Douglas A. Melton, PhD
Douglas A. Melton is Thomas Dudley Cabot Professor in the Natural Sciences, codirector of the Harvard Stem Cell Institute, and Chair of the Life Sciences Council in the Faculty of Arts and Sciences at Harvard University. Melton received a BS from the University of Illinois in 1975, a BA from Cambridge University in 1977, and a PhD in 1980 from Trinity College and the MRC Laboratory of Molecular Biology.
Melton served as assistant professor in Harvard's Department of Biochemistry and Molecular Biology from 1981 to 1984. Named an associate professor in 1984, and John L. Loeb Associate Professor of the Natural Sciences in 1987, he received tenure in 1988. Since 1993, he has served as a biologist at Massachusetts General Hospital; and since 1994, the year he was named a Howard Hughes Investigator, Melton has also held responsibilities as associate member of Children's Hospital in Boston. Named as Cabot Professor in 1999, he is a member of both the American Academy of Arts and Sciences and the National Academy of Sciences.
Melton has been the recipient of numerous awards, among them the Max Perutz Prize (1981); Camille and Henry Dreyfus Award (1981); Searle Scholar Award (1983–1986); American Society of Biochemistry and Molecular Biology Young Investigator Award (1991); George Ledlie Prize (1991); Richard Lounsbery Award, National Academy of Science (1995); Honorary Member, Japanese Biochemical Society (1996); and the Eliot P. Joslin Medal (2002).
He also has editorial responsibilities on several significant scientific journals including Science (1997–2001); Development, Neurobiology, and Cytokine & Growth Factor Reviews (2003); Regenerative Medicine, Proceedings of the National Academy of Sciences (editorial board), and Genome Biology (advisory board) (2003–2004).
Melton is a member of the NIH/NIDDK Ad Hoc Strategic Planning Group, Stem Cells and Developmental Biology (2000–present) and treasurer of the International Society on Stem Cell Research (2002–present). His research focuses on understanding how the pancreas normally develops in order to grow and develop pancreatic cells (Islets of Langerhans) in culture. His long-term goal is to be able to provide a source of insulin producing β cells for transplantation into diabetics.
John D. Gearhart, PhD
John D. Gearhart is the C. Michael Armstrong Professor at Johns Hopkins Medicine and Director of the Stem Cell Program, of the Institute for Cell Engineering at Johns Hopkins Medicine. He is professor of gynecology and obstetrics, physiology, and comparative medicine at the Johns Hopkins University School of Medicine and professor of biochemistry and molecular biology in the Bloomberg School of Public Health. Gearhart earned his doctorate at Cornell University, had fellowship training with Beatrice Mintz at the Fox Chase Cancer Center, and joined the faculty at Hopkins in 1979. Gearhart is a developmental geneticist and his research over the past two decades has been directed at understanding the molecular and cellular basis of human embryonic development. He has over 300 research publications in developmental genetics, from Drosophila to mice to humans. Gearhart is a leader in the development and use of human reproductive technologies and in the genetic engineering of cells.
In 1998 Gearhart and his research team at Johns Hopkins published a report on the derivation of pluripotent stem cells from primordial germ cells of the human embryo. These cells have the capacity to form all cell types and tissues present in the human body and are considered a major starting point for the development of a wide variety of cell-based therapies in the new field of regenerative medicine. Gearhart is a major spokesperson for the study and use of human stem cells derived from early embryonic tissues. His current research is focused on the basic science of stem cells, cell differentiation, and the generation cell-based therapies for a number of diseases and injuries, including juvenile diabetes, metabolic diseases of the liver, motor neuron loss, Parkinson's disease, spinal cord injury, stroke, heart disease, and cerebral palsy.
Ruth Lehmann, PhD
Born in Cologne, Germany, Ruth Lehmann was introduced to fly development first in Gerold Schubiger's lab at the University of Washington, Seattle, and then during her Diploma thesis in the laboratory of the late Jose Campos Ortega at the University of Freiburg, Germany, where she described the neurogenic genes in Drosophila. She completed her doctoral thesis in 1985 in the laboratory of Christiane Nüsslein-Volhard, where she participated in the identification of maternal effect genes that organize the embryonic axis in Drosophila. After postdoctoral training in Tübingen and at the MRC in Cambridge, UK in the laboratory of the late Mike Wilcox, she joined the Whitehead Institute and the faculty of MIT in 1988. Molecular characterization of nanos, pumilio, and oskar in her lab showed that RNA localization within a cell is tightly linked to translational regulation. In 1996 Lehmann moved to the Skirball Institute at NYU School of Medicine where she is an Investigator of the Howard Hughes Medical Institute and the Julius Raynes Professor of Developmental Genetics. Lehmann is director of the Developmental Genetics Graduate Program and the Helen and Kimmel Stem Cell Center at NYU. She is deputy editor in chief of the journal Development and a member of the American Academy of Arts Sciences and the U.S. National Academy of Sciences. Her lab uses genetic, molecular, and high-resolution imaging approaches to study germ cell specification, migration and survival in the embryo, and germ line stem cell maintenance in the adult.
Thomas M. Jessell, PhD
Thomas Jessell is Claire Tow Professor of Motor Neuron Disorders, and a Professor of Biochemistry and Molecular Biophysics, in the Center for Neurobiology and Behavior at Columbia University.
Thomas Jessell received his PhD from Cambridge University, in the UK, and was a research fellow of Trinity College, Cambridge. He was a postdoctoral fellow at Harvard Medical School, and was a Locke Research Fellow of the Royal Society. In 1981 he was appointed an assistant professor in the Department of Neurobiology at Harvard Medical School and in 1985 moved to Columbia University as an Investigator of the Howard Hughes Medical Institute. Jessell is a foreign associate of the U.S. National Academy of Sciences, a member of the Institute of Medicine, and a Fellow of the American Academy of Arts and Sciences. He is also a fellow of the Royal Society and of the UK Academy of Medical Sciences. He is the recipient of the Bristol-Myers Squibb Award for Distinguished Achievement in Neuroscience, the March of Dimes Prize in Developmental Biology, and the Ameritec Foundation Prize for research in spinal cord injury.
Jessell's research explores the cellular and molecular mechanisms that control the development and function of neural circuits that control locomotor behaviors organization of the spinal cord. His studies have shown that spinal motor neurons and interneurons achieve their distinct identities and characteristic position of generation through the actions of two classes of inductive signaling molecules, members of the Hedgehog (Hh) and bone morphogenetic protein (BMP) families. He has found that the sonic hedgehog protein functions as a morphogen—an inductive signal that specifies different ventral neuronal cell types at distinct concentration thresholds. His work has also defined many of the key genetic targets of Sonic hedgehog signaling that impose distinct identies on spinal cord neurons and determine their patterns of connectivity. In addition, his work has defined signaling factors that help to guide developing axons to their targets and to establish selective synaptic connections.
Domenico Accili, MD
Domenico Accili is professor of medicine at Columbia University, attending physician at Columbia-Presbyterian Hospital, and director of the Columbia University Diabetes and Endocrinology Research Center in New York, NY. A graduate of the University of Rome School of Medicine in Italy, he trained in Medicine at the University Hospital, Agostino Gemelli, also in Rome. Following a Fogarty Fellowship in the Diabetes Branch of the National Institute of Diabetes and Digestive and Kidney diseases, he became chief of the Section on Genetics and Hormone action of the National Institute of Child Health at the National Institutes of Health in Bethesda, Maryland. Since 1999, he has served on the faculty at Columbia University.
Accili is best known for his research on the pathophysiology of type 2 diabetes, the integrated physiology of insulin action and mechanisms of pancreatic β-cell turnover. His interest in pancreatic development stems from studies in his laboratory on the mechanisms of β-cell failure in diabetes. Accili's laboratory has identified a family of DNA-binding proteins that regulate the response to insulin and glucose in many cell types, including pancreatic β cells. He has received numerous awards for his work, including the 2003 Lilly Award for Outstanding Scientific Achievement by the American Diabetes Association. His work has been published in over 100 peer-reviewed articles in scientific journals. He currently serves as an associate editor of the Journal of Clinical Investigation. He is a member of several advisory panels, including the NIH Beta Cell Biology Consortium and the Special Statutory Funding for Type 1 Diabetes. His work is supported by the NIH, the American Diabetes Association, and the Russ Berrie Foundation.
Ali H. Brivanlou, PhD
Ali Brivanlou, a developmental biologist, heads the Laboratory of Molecular Embryology at the Rockefeller University. Much of his research focuses on the molecular events and cellular interactions that regulate the emergence of key structures in the early embryo. In studies of frogs, for example, Brivanlou and his colleagues have worked to identify the molecular signals that control neural development and track down the genes that orchestrate those signals. In the course of this research, he has made several influential discoveries, including the unanticipated finding that all embryonic cells will develop into nerve cells unless they receive signals directing them toward another fate.
Brivanlou and his research group have studied molecular signals involved in the formation of the eye, heart, pancreas, and other organs. Information obtained from this work, conducted in animal models, provides a strong foundation for his ongoing research involving human embryonic stem cells. In 2003, he and his colleagues conducted a genome-wide analysis of gene expression that led to the establishment of a molecular signature for the state of "stemness" in mouse and human embryonic stem cells. Their current work focuses on the molecular dissection of the defining properties of embryonic stem cells, their capacity for self-renewal, and their ability to differentiate into a range of cell types.
Fundamental studies in the Brivanlou laboratory, while offering insights into human development, may also help to advance the treatment or prevention of cancer and a broad range of other clinical conditions. These include development-related disorders, such as schizophrenia and epilepsy, neurodegenerative diseases, and diabetes. Brivanlou is also a leader in the international effort to establish scientific standards for human embryonic stem cell research.
Brivanlou received a master's degree in biochemistry from the Université des Sciences et Techniques du Languedoc in Montpellier, France. From 1983 to 1985, he was a research scientist at International Genetic Engineering, Inc., in Santa Monica, CA. He went on to earn a PhD in molecular biology from the University of California, Berkeley, in 1990. The following year, Brivanlou moved to Harvard University as a postdoctoral fellow in the laboratory of Douglas Melton. He joined the Rockefeller faculty as an assistant professor and head of laboratory in 1994 and was promoted to professor in 2000.
In 1996, Brivanlou received a Presidential Early Career Award for Scientists, the U.S. government's most prestigious honor for young investigators. His other honors include an Irma T. Hirschl Career Scientist Award, and Searle Scholar Award, a Klingenstein Fellowship, a McKnight Scholar Award, a Wilson Stone Memorial Award, and a John Merck Scholar Award.
Kenneth R. Chien, MD, PhD
Kenneth Chien is an internationally recognized biologist specializing in cardiovascular science, as well as a pioneer in developing new therapeutic strategies to prevent the onset and progression of heart failure. Since July 2005, Chien has returned to Boston as scientific director of the Cardiovascular Research Center at Massachusetts General Hospital and professor of cell biology at Harvard Medical School. He is a member of the Harvard Stem Cell Institute, where he leads the university-wide Cardiovascular Stem Cell Biology Program. Upon his return to the Harvard community, he was awarded the distinction of the first endowed chair of the Charles Addison & Elizabeth Ann Sanders Professor of Medicine. Prior to his MGH/HMS appointments, Chien directed the Institute for Molecular Medicine at the University of California at San Diego (UCSD). He is a professor emeritus at UCSD, and continues his appointment as an adjunct professor of The Salk Institute.
A graduate of Harvard University, Chien went on to earn his MD and PhD from Temple University in Pennsylvania. After completing his internship, residency, and cardiology fellowship training at the University of Texas Southwestern Medical School in Dallas, he joined the faculty of the UCSD Departments of Medicine and Cardiology and the Center for Molecular Genetics. Subsequently, Chien became the director of the UCSD Institute of Molecular Medicine and directed the joint UCSD-Salk Institute National Institutes of Health Molecular Medicine Training Program. Given his longstanding interest in training physician-scientists, he has served as an advisor/panel member of several private biomedical foundations, including the Doris Duke Charitable Foundation and the Wellcome Trust. He also has served as a senior consultant and board member to several biotechnology and large pharmas over the past decade, fostering collaborative ties between academia and the private sector. His most recent accomplishments include the establishment of a new Institute of Molecular Medicine at Peking University, currently the premier site for cardiovascular science and medicine in China. He has received several awards for his work, including the Pasarow Foundation Award and the Walter B. Cannon Award of the American Physiological Society.
Chien has conducted groundbreaking research focused on the molecular pathways of cardiac development and disease, much of which has been published in the top tier journals in the field of biomedical science, including Cell, Science, and Nature. Most recently, his laboratory discovered the "progenitor cells" (similar to stem cells) residing in the heart. These cells signal a particularly exciting breakthrough, as they are capable of generating functioning heart muscle cells. Since its publication in Nature in 2005, this finding has recently been recognized as one of most highly cited papers in the biomedical field. Recently, the Chien lab has discovered a "master" cardiovascular stem cell that can give rise to all three major cell types in the heart: cardiac, smooth muscle, and endothelial, and is implicated in formation of heart muscle, the heart pacemaker system, and the coronary arteries. Since this master cardiovascular stem cell can be cloned from embryonic stem cells, this new finding has significant implications both for the study of the heart development, drug discovery, and disease target identification, and for longer term potential therapeutic application of the cells to repair and replace damaged heart, pacemaker, and vascular tissue.
Kevin C. Eggan, PhD
Kevin C. Eggan is an assistant professor of biology in the Department of Molecular and Cellular Biology at Harvard University, a principal investigator at the Harvard Stem Cell Institute, and an assistant investigator at the Stowers Medical Institute. Eggan received a PhD in 2003 from the Massachusetts Institute of Technology in biology.
Eggan served as a junior fellow in the Harvard University Society of Fellows from 2003 to 2005. He worked as a postdoctoral associate at the Whitehead Institute for Biomedical Research under Rudolf Jaenisch from 2002 to 2003, and served as a predoctoral fellow at the NICHD Laboratory of Molecular Genetics at the National Institutes of Health under Robert Crouch from 1996 to 1998.
Eggan has recently been honored with a MacArthur Fellowship. He was named a Basil O'Conner Scholar by the March of Dimes in 2005, which includes a two-year fellowship, and received a Harvard Junior Fellowship, which also includes a two-year award. In 2003, he received the Harold M. Weintraub Graduate Student Award from the Fred Hutchinson Cancer Research Center; he was selected Biovision.nxt Fellow by AAAS/Science Next Wave. He served as the Abraham J. Siegel Outstanding Graduate Fellow at the Whitehead Institute, 2000–2001, and received an Intramural Research Training Award, 1996–1998.
Eggan is also serving on the Scientific and Medical Accountability Standards Working Group at the California Institute for Regenerative Medicine. He is a member of the Medical Advisory Board of the New York Stem Cell Foundation and a member of the National Center for Research Resources Special Emphasis Panel of the National Institute of Health, 2005, 2006.
Currently, Eggan and his group investigate the mechanisms regulating epigenetic reprogramming after somatic cell nuclear transfer. Additionally, they are developing human embryonic stem cell lines that can be used to model and treat human neurodegenerative disease.
Elaine Fuchs, PhD
Elaine Fuchs is a world leader in skin biology and its human genetic disorders, which include skin cancers and life-threatening genetic syndromes such as blistering skin disorders. From nearly the beginning of her scientific career, Fuchs focused on the molecular mechanisms that underlie the development and differentiation of the epidermis and its appendages from multipotent stem cells. Throughout her studies, she has continually used the basic biology that she uncovered to elucidate how perturbations of these mechanisms result in disease.
She has systematically applied molecular and genetic approaches to these problems. In doing so, Fuchs pioneered the use of reverse genetics, an unconventional and now textbook approach to start with understanding how proteins function and then work up to the human diseases they cause when defective. She initially conceived and applied this strategy to elucidate the functions and genetic basis of the first intermediate filament disorder, now a group of nearly 20 related but distinct human disorders that affect not only skin, but also muscle, the nervous system, liver and other tissues and organs of the body.
Recently, she has applied her findings to devise creative approaches for identifying, isolating and characterizing the multipotent stem cells from skin and determine how they respond to various external cues to select their fates to become hair follicles, sebaceous glands or epidermis. In facing the problem of progressing from a stem cell to a tissue, Fuchs's laboratory now tackles how cells coordinate changes in transcription, cell polarity, adhesion, and cytoskeletal dynamics. She is widely credited for bringing dermatology into a modern day science. She has published over 200 papers, mostly in high-profile scientific and medical journals.
Fuchs received her PhD in biochemistry from Princeton University in 1977. She conducted postdoctoral research at the Massachusetts Institute of Technology in the Laboratory of Howard Green. In 1980, she joined the faculty at the University of Chicago. When she left Chicago to accept a position at the Rockefeller University in 2002, Fuchs was the Amgen Professor of Basic Sciences and an Investigator of the Howard Hughes Medical Institute. Fuchs's many awards and honors include the Presidential Young Investigator Award, the Richard Lounsbery Award from the National Academy of Sciences, the Novartis-Drew Award for Biomedical Research, the Dickson Prize in Medicine and the FASEB Award for Scientific Excellence. She is a member of the National Academy of Sciences, the Institute of Medicine of the National Academy of Sciences, the American Academy of Arts and Sciences and the American Philosophical Society, and she holds honorary doctorates from Mt. Sinai/New York University School of Medicine and from the University of Illinois, Champaign-Urbana. Fuchs is also a past president of the American Society of Cell Biology.
Konrad Hochedlinger, PhD
Konrad Hochedlinger is an assistant professor at Massachusetts General Hospital and is also on the principal faculty of Harvard Medical School and the Harvard Stem Cell Institute. He earned his BS in genetics from the University of Vienna and both his MS in Genetics (1999) and PhD in mammalian development (2003) at the Research Institute of Molecular Pathology in Vienna, Austria. Previously, Hochedlinger worked as a visiting graduate student and a postdoctoral associate/fellow in the laboratory of Rudolf Jaenisch at the Whitehead Institute for Biomedical Research.
In 2003 Hochedlinger was awarded a predoctoral fellowship from the Boehringer Ingelheim Foundation and in 2005 he was awarded a postdoctoral fellowship from the Genzyme Foundation. Hochedlinger has also been widely published in scientific and medical journals.
Gordon Keller, PhD
Gordon Keller is a professor in the Department of Gene and Cell Medicine at Mount Sinai School of Medicine. He received his Bachelor's of Science in biochemistry at the University of Saskatchewan and his PhD in immunology at the University of Alberta.
Keller has served as a member of the Basel Institute for Immunology (1983–1988); assistant faculty member in the Department of Medicine at the National Jewish Center for Immunology and Respiratory Medicine (1992–1999); assistant professor in the Department of Biochemistry, Biophysics and Genetics at the University of Colorado Health Sciences Center (1990–1995); and associate professor in the Department of Immunology at the University of Colorado Health Sciences Center (1995–1999). In 2000, he was awarded the Outstanding Faculty Achievement Award in Basic Sciences at Mount Sinai School of Medicine and in 2005 he served as the president of the International Society for Stem Cell Research in San Francisco.
Selected peer-reviewed publications include Nature, Development, and Methods in Enzymology.
Arnold Kriegstein, MD, PhD
Arnold Kriegstein is director of the Institute for Regeneration Medicine and a professor of neurology at the University of California, San Francisco. Prior to his new assignment, he worked as a professor of neurology at the College of Physicians & Surgeons at Columbia University, Yale University, and Stanford University from 1981–2001.
Kriegstein is known and highly respected in his community for his research in the area of neocortical development, neural differentiation and development. He has received several awards such as a Stanford University William M. Hume Faculty Scholar, a Javitts Award from the NIH, and has coauthored and reviewed numerous medical publications in neuroscience.
He received his bachelor's degree in 1971 from Yale University, and his MD and PhD degrees from New York University.
Alison Murdoch, MD, FRCOG
Alison Murdoch is a professor of reproductive medicine, gynaecologist, and head of Newcastle Fertility Centre at Life, Newcastle upon Tyne, U.K. She completed her undergraduate medical studies in Edinburgh before moving to the Northeast of England to complete her training in Obstetrics and Gynaecology. Her MD thesis was in reproductive medicine and this stimulated an interest in infertility. She established the Newcastle Fertility Centre at Life, which is now recognised as one of the leading NHS fertility centres in the UK. Murdoch is past chair of the British Fertility Society, the national society which represents all those involved in the provision of care for the infertile patient.
Her principal research interests are the regulation of early human preimplantation development and the ethical and regulatory issues relating to the donation of embryos and eggs for research, including human embryonic stem cell derivation and nuclear transfer. She is part of the North-East England Stem Cell Institute (NESCI), a successful collaboration between the Universities of Newcastle and Durham based at the International Centre for Life. The group has derived several embryonic stem cell lines and has been granted a licence from the HFEA to develop the technology of nuclear transfer for stem cell derivation (therapeutic cloning). The first successful human nuclear transfer procedure in which a blastocyst was grown was reported in August 2005.
Amit N. Patel, MD, MS
Amit Patel is director of the Center for Cardiac Cell Therapy at the University of Pittsburgh Medical Center, director of the Center for Cardiovascular Cellular Therapy, McGowan Institute for Regenerative Medicine, and assistant professor of surgery at the University of Pittsburgh School of Medicine.
Patel, a cardiothoracic surgeon, is internationally recognized as a pioneer of adult cardiac stem cell research and therapies. In a decade of providing cardiac care, Patel has sought to improve the treatment of heart conditions, particularly by restoring strength and function to heart muscle with adult stem cells. Patel has performed over 100 adult stem cell surgeries worldwide, and has received U.S. Food and Drug Administration approval for two UPMC trials using bone marrow-derived stem cells. As the director of the new Center for Cardiac Cell Therapy, Patel plans to advance his clinical and research efforts to further understand the benefits of adult stem cell treatments.
Patel received his medical degree from Case Western Reserve University and completed residency programs and fellowships at both Baylor University and the University of Pittsburgh. He received his MS degree in immunophysiology at Youngstown State University.
Shahin Rafii, MD
Shahin Rafii is the Arthur B. Belfer Professor of Genetic Medicine and Investigator of Howard Hughes Medical Institute at Weill-Cornell Medical College. Rafii, who is a board certified hematologist-oncologist, is engaged in patient care as well as basic and translational research. He has expertise in basic tumor biology as well as vascular and stem biology. He was recently appointed to spearhead the Ansary Stem Cell Center for Regenerative Medicine at Weill-Cornell.
Rafii graduated cum laude from Cornell University in 1982, with a degree in chemistry and was awarded Phi Beta Kappa. He received his MD degree from Albert Einstein College of Medicine with honors and was elected to AOA society in 1986. Subsequently, in 1989, he completed his internship and residency in internal medicine followed by a fellowship in hematology-oncology at Weill-Cornell in 1992. In 1986 he completed his postdoctoral training in vascular and hematopoietic stem cell biology under supervision of Ralph Nachman at Weill-Cornell. He became a full professor in genetic medicine in 2002, at which time he was appointed to be the codirector of the Ansary Stem Cell Center.
Rafii is funded by NIH's Heart, Lung, and Blood Institute, and is an active charter member of the Tumor Microenvironment Study Section at the National Cancer Institute. He is an elected member of the American Society of Clinical Investigation (Young Turks), an American Cancer Society Scholar, and a Translational Researcher of the Leukemia and Lymphoma Society.
He is a consulting editor for the Journal of Clinical Investigation and is a member of the editorial board of the Stem Cells Journal and Journal of Cardiovascular Regeneration. He is an ad hoc reviewer for Nature, Science, and Nature Medicine journals.
Rafii is principal inventor in several patents on therapeutic use of vascular stem cells for organ regeneration.
Renee A. Reijo Pera, PhD
Renee Reijo Pera is the codirector of the Human Embryo Development and Stem Cell Research Center and associate professor of obstetrics, gynecology & reproductive sciences, at the University of California at San Francisco. Her research is aimed at understanding the genetics of human embryo growth and development and in characterizing the properties of human embryonic stem cells, especially their ability to differentiate to all cell types including germ cells. She has received numerous awards throughout her career and most recently was named Outstanding Faculty Mentor at UCSF in 2005.
Pera received her Bachelor of Science degree from the University of Wisconsin (Superior), her doctoral degree from Cornell University in Ithaca, New York, and her postdoctoral training at the Whitehead Institute for BioMedical Research at the Massachusetts Institute of Technology in Cambridge, Massachusetts. She joined the UCSF faculty in 1997.
Warren Sherman, MD, FACC, FSCAI
Warren Sherman is associate professor of clinical medicine at Columbia University College of Physicians and Surgeons and director of cardiac cell-based endovascular therapies at the Center for Interventional Vascular Therapy at New York-Presbyterian Hospital/Columbia University Medical Center.
Sherman earned his Bachelor of Science degree at Massachusetts Institute of Technology and medical degree at the State University of New York, Upstate Medical Center. Following an internal medicine residency at the University of Rochester, he spent three years at the Oregon Health Sciences University as a fellow in cardiovascular diseases, where many of the cardiac procedures that form the foundation of modern interventional cardiology originate.
In 1983, Sherman moved to Mount Sinai Hospital in New York to investigate new techniques for treating patients with acute myocardial infarction. It was at that time that the first thrombolytics (clot-dissolving medications) were being evaluated in patients. In 1989, he shifted to a fully clinical role, and created the Interventional Cardiology Program at Beth Israel Medical Center in New York City.
With a deepening interest in myocardial regenerative techniques, Sherman pioneered a technique for injecting stem cells into the heart. In Rotterdam in May 2001, he performed the first catheter-based injection of adult stem cells into the heart of a patient with congestive heart failure due to a previous heart attack. This technique was then brought to the U.S., where he performed a similar procedure at Mount Sinai Hospital in April 2003. As director of cell therapy at Mount Sinai Hospital, Sherman was the principal investigator of a multicenter clinical study of autologous skeletal myoblast injections for patients with congestive heart failure and the lead investigator on numerous translational studies. Sherman has authored or coauthored numerous publications in the emerging field of myocardial regeneration.
Hongjun Song, PhD
Hongjun Song is currently assistant professor of neurology and neuroscience at the Institute for Cell Engineering at Johns Hopkins University School of Medicine. Among his many awards, Song is a McKnight Scholar Award recipient, as well as a Klingenstein Fellowship Award winner. Song has served as a journal peer reviewer for numerous journals, including Cell, Neuron, Molecular and Cellular Neurobiology, Journal of Neuroscience, and Gene Therapy. He has also been widely published in peer-reviewed publications, some of which include Neuron, Nature, Science, and Neuroscientist.
Song earned his PhD at the University of California, San Diego. He is a member of the Society for Neuroscience, Society for Experimental Biology and Medicine, and International Brain Research.
Allen M. Spiegel, MD
Allen M. Spiegel is the Marilyn and Stanley M. Katz Dean of the Albert Einstein College of Medicine of Yeshiva University. Prior to becoming dean in June 2006, he was director of the National Institute of Diabetes & Digestive Diseases & Kidney Diseases (NIDDK) at the National Institutes of Health. Spiegel began his career at the NIH in 1973 as a clinical associate in its endocrinology training program. He then served as a senior investigator in the Metabolic Disease Branch from 1977 to 1984. In 1985, he was appointed chief of molecular pathophysiology, and then chief of the Metabolic Diseases Branch. In 1990, he was appointed director of the NIDDK's Division of Intramural Research. He served in these various capacities until his appointment as director of the NIDDK in 1999.
Spiegel, a widely renowned physician-scientist and endocrinologist with extensive experiences in translational research programs, is a member of the Institute of Medicine of the National Academy of Sciences. Spiegel's research has centered on G protein-regulated signaling dysfunction in human disease, and his work on signal transduction helped to clarify the genetic basis of several endocrine diseases. He has published extensively, with more than 250 peer-reviewed papers and 100 reviews and book chapters to his name, as well as two books on G proteins. Spiegel earned his bachelor's degree summa cum laude and Phi Beta Kappa from Columbia University in 1967. He received his MD degree cum laude from Harvard Medical School in 1971 and completed his clinical training at Massachusetts General Hospital.
Lorenz Studer, MD, PhD
Lorenz Studer is director of the Laboratory of Stem Cell & Tumor Biology at Memorial Sloan-Kettering Cancer Center, and a pioneer in fetal tissue research whose work focuses on stem cells and brain repair. His lab's accomplishments include the in vitro derivation of midbrain dopamine neurons from adult somatic cells via nuclear transfer and from a novel type of pluripotent parthenogenetic stem cell in monkeys. Studer is an assistant member of the neurosurgery & cellular biochemistry and biophysics departments at the Sloan-Kettering Institute and an assistant professor of neuroscience at Cornell University.
A native of Switzerland, Lorenz Studer graduated from medical school in 1991 and received his doctoral degree in neuroscience at the University of Bern in 1994. While there, he initiated studies with Christian Spenger, leading to the first clinical trial of fetal tissue transplantation for Parkinson's disease in Switzerland. He later moved to the the National Institutes of Health (NIH) in Bethesda, Maryland, where he worked in the laboratory of Ronald D. McKay. At the NIH he pioneered techniques that allow the generation of dopamine cells in culture from dividing precursor cells. In 1998, he demonstrated that upon transplantation, such dopamine cells generated in culture improve clinical symptoms in Parkinsonian rats. Studer then went on to show that virtually unlimited numbers of cultured mouse dopamine cells could be obtained from embryonic stem cells.
Hynek Wichterle, PhD
Hynek Wichterle is an assistant professor holding a joint appointment in the departments of pathology and neurology, and the Center for Neurobiology and Behavior at Columbia University Medical Center. He received his MS degree from Charles University in Prague and his PhD degree from the Rockefeller University. He did his postdoctoral research in Tom Jessell's lab at Columbia University and became assistant professor at the university in 2004.
Alan Dove is a science writer and reporter for Nature Medicine, Nature Biotechnology, and Bioscience Technology. He also teaches at the NYU School of Journalism, and blogs at http://dovdox.com.
On the evening of August 9, 2001, George W. Bush announced the first major policy decision of his presidency, on an issue that would have seemed arcane just a few years earlier: stem cells. Under the new policy, federal funding for human embryonic stem cell research would be restricted to work on 71 cell lines that the Administration had identified. The majority of these lines turned out to be useless.
What do we know about stem cells, and what can we do with them?
Founded in 2005, the New York Stem Cell Foundation (NYSCF) is a privately-funded foundation supporting human embryonic stem cell research in the search for cures of major diseases. The foundation opened the first privately-funded human embryonic stem cell laboratory in New York in March 2006 to serve as a "safe haven" where scientists from academic medical centers in the New York area and throughout the East Coast can conduct advanced human embryonic stem cell research free of the federal restrictions that—since that fateful evening in August—have limited the scope of government-supported work.
The organization's missions are: to support scientists engaged in human embryonic stem cell (hESC) research and somatic cell nuclear transfer (SCNT), through grants, fellowships and symposia; to educate the public about the importance and potential benefits of human embryonic stem cell (hESC) research and somatic cell nuclear transfer (SCNT); and to establish new collaborative, state-of-the-art research facilities supported entirely with private funds and directly focused on curing disease.
When the NYSCF held its first Translational Research Conference on October 23–24, 2006, at the Rockefeller University, the first talks provided an update on the current legal landscape of stem cell science.
For leading stem cell researchers—many of whom assembled at this historic conference—the focus was scientific rather than political. The recurring theme of the day-long conference was, exactly what do we know about stem cells, and what can we do with them? Scientists from around the world discussed the most recent findings in the most promising research areas: somatic cell nuclear transfer (SCNT), diabetes, heart disease, cancer, and neurology.
Somatic cell nuclear transfer
Somatic cell nuclear transfer (SCNT) is a technique whereby the nucleus of a somatic cell is injected into an enucleated egg. The goal is to reprogram the DNA of the somatic cell so that it regains the ability to generate all of the cell types of the organism. Scientists working with human cells are interested in using SCNT both as a reproductive technology and as a way of producing stem cell lines, which they hope to use to replace a variety of tissues that don't regenerate on their own. The conference featured presentations highlighting the state of the art of this technique. Among the findings were the following:
- While somatic cell nuclear transfer, or "cloning" is still years away from the clinic, it is already a useful tool for researchers.
- Diseases like ALS have diverse etiology, which cloned embryonic stem cell lines can mimic in tissue culture.
- The mechanisms of egg reprogramming in early development suggest new ways to direct stem cell reprogramming in the laboratory.
- Chemical treatment may obviate the need for feeder cells in stem cell cultures.
- Nuclear transfer remains a technically challenging procedure, especially with human oocytes.
Diabetes and autoimmune disease
Some adult tissues appear to maintain stem cells that are not capable of diffentiating into every cell type, but which can regenerate a few kinds of cells. For example, the skin sheds dead cells and replaces them with new ones from a pool of adult stem cells. Other tissues do not appear to have such regenerative capacity. When the insulin-producing β cells of the pancreas are destroyed by an autoimmune reaction, for example, they are not replaced and type 1 diabetes results. Researchers are exploring a number of ways to replace β cells and investigating normal pancreatic development to inform their approach. Highlights from this session include the following:
- Autoimmune diseases like type 1 diabetes might respond well to stem cell-based therapies.
- Targeting a single gene might stimulate the pancreas to regenerate itself.
- Cultured embryonic stem cells can differentiate into pancreas-like cells, but it's unclear whether they will function in vivo.
- Researchers should be careful not to oversell the promise of stem cells in type 1 diabetes, as the field is still in its infancy.
- The number of stem cells present when the pancreas starts growing seems to determine the organ's ultimate size.
Researchers working on type 1 diabetes may be encouraged by reports from the world of cardiology stem cell research, where embryonic stem cells can be stimulated to differentiate into cardiomyocytes. Yet all stem cell researchers face the problem that the path from totipotent stem cell to fully differentiated cell is not clear. Some scientists are tracing the lineage of cells using fluorescent markers while others are looking for genes and growth factors that are required to commit a cell to a specific developmental pathway. Presentations at the conference indicated some recent findings showing progress in applying stem cell research to cardiology:
- A single type of stem cell, marked by the Islet-1 protein, gives rise to all of the cells in the adult heart.
- Injecting stem cells into heart tissue during bypass surgery seems to improve outcomes, but it's still unclear why.
- Scientists and surgeons are still debating whether adult bone marrow stem cells are a realistic source for heart stem cells.
- Patients who receive stem cells derived from their own bone marrow are less likely to mount immune responses against the new tissue.
Oncologists often see the plasticity that other scientists are trying to reproduce: tumors can dedifferentiate while stimulating new blood vessel growth to feed themselves. Researchers are very interested in understanding the mechanism by which tumor cells become pluripotent because it could lead to ways to coax other cell types to do so. Moreover, an understanding of the regulation of blood vessel growth, or angiogenesis, is critical both for the treatment of cancer, where cutting off the nutritional support for tumors is important, and for scientists trying to regenerate tissues that may have lost the supporting vascularization required for survival. Among the topics under discussion in this session were the following:
- Tumors turn back the developmental clock to adopt embryonic-like growth patterns, surprising stem cell biologists.
- Treating cultured stem cells with appropriate growth factors can stimulate angiogenesis and the formation of vascularized tissue.
- A balance between the signaling molecules Oct-4 and Cdx-2 seems to regulate stem cell reprogramming in tumors.
- The Wnt signaling pathway guides the differentiation of skin stem cells into hair follicles.
Neuroscientists face the same challenges as other researchers trying to replace fully differentiated nonregenerating cell types. Thus, they are also studying basic stem cell biology, cell lineages, and factors required to stimulate differentiation to the appropriate cell fate. Once these difficulties are surmounted, scientists may be faced with the extraordinary complexity of restoring appropriate connections in the brain and spinal cord. The conference also included an update on recent discoveries in the effort to find ways to repair neurological damage:
- Currently available stem cell lines vary widely in their growth rates, and some labs have produced better lines than others.
- Stem cell-derived motor neurons are functional when transplanted into chick embryos.
- An emerging network of signals directs stem cells in the adult brain to become new neurons.
- Radial glial cells, long considered mere scaffolding, actually appear to direct much of the cerebrum's development.
Stem cell biologists are attempting to recapitulate development from beginning to end, and this is no easy feat. But the enormous benefits that will be reaped upon success ensure that the endeavor will not be abandoned any time soon. According to conference cochair Harold Varmus (Sloan-Kettering Institute for Cancer Research), "These technologies lead to results that already both overturn long-held dogma in the field and present a number of incredibly complicated issues." The NYSCF will be among those seeking to resolve those issues as the science advances.
Kevin Eggan, Harvard University
Renee Reijo Pera, University of California, San Francisco
Ali Brivanlou, The Rockefeller University
Alison Murdoch, Newcastle Fertility Centre at Life
Send in the products of somatic cell nuclear transfer
Clone. To the average person on the street, the word conjures a bizarre montage of fact and fiction, from Dolly the sheep grazing in a Scottish field to Huxleyesque farms of sterile baby incubators waiting to be harvested. To researchers, cloning is far more mundane. It is a generic term that can mean cutting and splicing DNA, isolating pure cultures of an organism, screening whole genomes for specific genes, or transferring nuclei from one cell type to another.
The two interpretations overlap at somatic cell nuclear transfer (SCNT), the correct term for the procedure that produced Dolly, the "clone" generated from a six-year-old ewe at the Roslin Institute in 1996. Transferring the nucleus of a somatic cell, like a skin cell, into an enucleated egg, then "reprogramming" the nucleus to restart the developmental script from the beginning, can produce an embryo—and subsequently an adult animal—that is genetically identical to the skin cell donor.
In principle, SCNT could yield everything from self-regenerating populations of nerve cells for treating debilitating diseases to new reproductive technologies for infertile couples. In practice, SCNT remains an exceedingly difficult technique that is still years away from application in the clinic.
Creating in vitro models of neuronal disease with SCNT
Kevin Eggan (Harvard University) discussed his efforts to use SCNT to develop new model systems for amyotrophic lateral sclerosis (ALS). ALS, also known as Lou Gehrig's disease, is a fatal neurodegenerative condition that strikes patients in the prime of their lives.
While about 10% of ALS cases are hereditary, the other 90% appear to arise spontaneously. Eggan hopes to use SCNT to reproduce this diverse etiology, by transplanting nuclei from somatic cells of ALS patients into donor oocytes. Growing the oocytes into blastocysts, then stimulating the resulting embryonic stem cells to become neurons, should yield custom-built in vitro models of each patient's disease.
Custom models of each patient's disease will speed ALS research.
To test the strategy, Eggan and his colleagues started with an existing mouse model of ALS. About 2% of ALS cases stem from a mutation in the superoxide dismutase gene, and mice carrying this mutation in a transgene develop ALS-like pathology. The researchers crossed these mice with a strain that expresses the green fluorescent protein in motor neurons. They derived embryonic stem cells from the hybrids, then stimulated the stem cells to differentiate into neurons. As the neurons differentiate, they begin to glow green, allowing the researchers to track the cells' fates in tissue culture.
The scientists can keep the resulting neurons alive for more than two months, but the cells do not grow as well as wild-type controls. Interestingly, superoxide dismutase forms aggregates in the mutant cells, just as it does in the motor neurons of humans with ALS, suggesting that the model is indeed mimicking the disease.
"I think it's an encouraging start. We're only just beginning to look at these phenotypes in culture, but I think it's fair to say that we can recapitulate some of the histopathological phenotypes that are seen in ALS in these cells," says Eggan.
Changes in gene expression upon nuclear reprogramming
Renee Reijo (University of California, San Francisco) began her talk at the beginning, with a review of the first steps in embryonic development. Immediately after fertilization, a human egg must reprogram itself to start transcribing the genes necessary for embryo formation. At the same time, it must absorb the new DNA donated by the sperm, and reprogram it as well.
"The whole object of the first few days of life is to reprogram the nuclei of the oocyte and the sperm to that of an embryo," says Reijo, "so reprogramming is a very natural function of the oocyte."
That's an important point for researchers working on SCNT, where reprogramming the donor nucleus is a critical hurdle. Probing the natural version of the process, Reijo and her colleagues used microarrays to compare gene expression patterns between eggs and early embryos. They found that the total amount of RNA decreases dramatically over the first three days of development, corresponding to a vast downregulation of oocyte RNA expression, followed by an increase in embryonic RNA expression.
The same pattern occurs even in embryos that have arrested their development at the four-cell stage. Embryonic arrest is a major cause of fertility treatment failure in the clinic, so the researchers are now trying to determine which post-reprogramming step is causing the arrest.
Weaning stem cells from their feeders
Ali Brivanlou (The Rockefeller University) took the discussion on a slight digression from SCNT to discuss an important related issue: what is the essence of "stemness?" The question is not as mystical as it sounds. From the laboratory to the Senate floor, precisely defining the characteristics of a stem cell is a tricky problem.
As a working definition, most researchers say that a stem cell is a cell capable of reproducing itself, and also producing descendants that can differentiate into other cell types. However, many of the stem cell lines used in research labs must grow alongside "feeder cells" to remain self-renewing and undifferentiated, suggesting that they lack some characteristics of true embryonic stem cells.
To study the issue, Brivanlou and his colleagues derived a new line of stem cells. Video microscopy showed that the new cells form colonies with their feeders, and cells constantly migrate in and out of the colonies. The rapid turnover makes interesting television, but complicates the research. "It's impossible to dissect the function of human stem cells when they are contaminated with this kind of background," says Brivanlou.
Moving quickly through an impressive body of additional work, Brivanlou summarized his group's subsequent findings with the new cell line. In one major breakthrough, the researchers discovered that a pigment compound originally isolated from snails, 6-bromoindirubin-3′-oxime, allows the new stem cells to grow in the absence of feeder cells. When cultured this way, the cells show substantially less migration in and out of their colonies, suggesting that the movements were actually a product of being co-cultured with feeder cells.
"I would conclude very simply that most of these effects are due to the artifact of co-culture between mouse and human cells and [have] nothing to do with the ability of a human cell to behave," says Brivanlou.
Technical challenges of SCNT
Alison Murdoch, (Newcastle Fertility Centre at Life) the final speaker of the group, addressed the difficult technical realities of SCNT. Though the public perceives it as brand-new science, the history of SCNT actually dates back to 1952, when researchers successfully "cloned" frogs with the technique. That work proved the totipotency of stem cells—their ability to produce all types of tissue.
SCNT has been undergoing a renaissance, but the underlying methods remain extremely difficult.
SCNT has been undergoing a renaissance since the 1990s, but the underlying methods remain extremely difficult. Even the first step, removing the nucleus of an egg cell while leaving the rest of the egg intact, requires substantial technical skill. Other challenges include scanty information about the timing and mechanisms of egg reprogramming, and the possibility that common methods like fluorescence microscopy could damage the cell's DNA.
"It's complicated, the science, and I think we sometimes give the impression to laypeople that it's easier than it is," says Murdoch.
When working with human eggs, researchers also have difficulty getting enough starting material. Compared to common embryological models like frog eggs, "human eggs are not only very difficult to get hold of, but they're also very small to handle," says Murdoch, whose research focuses on both assisted reproduction and other therapeutic uses of human SCNT.
Despite these challenges, Murdoch and her colleagues recently succeeded in deriving human blastocysts after transferring somatic cell nuclei into donated oocytes. The procedure's success rate is still only 10%–30%, but the team is striving to improve that.
Pointing to a continuous series of advances since the 1978 birth of Louise Brown, the first "test tube baby," Murdoch urges both researchers and policymakers not to shortchange SCNT: "If we don't go ahead and do this work now, I think it's the next generation that will chastise us."
Allen Spiegel, Albert Einstein College of Medicine
Gordon Keller, Mount Sinai School of Medicine
Domenico Accili, Columbia University
Douglas Melton, Harvard University
A body divided
A carpenter hammers his thumb on Monday, and by Friday the bruise has healed. An alcoholic goes on the wagon, and her liver starts to repair itself immediately. A child develops an allergy, but later becomes tolerized to the allergen.
The body's capacity for regeneration and recovery is often astonishing. Unfortunately, it is also uneven. The carpenter who amputates his thumb rather than hammering it will not grow a new one. Liver damage may heal, but brain damage may not. And while the immune system usually limits the occasional overreaction, sometimes it doesn't.
Type 1 diabetes is the medical equivalent of a perfect storm.
In type 1 diabetes, two major flaws in the body's healing systems align, forming the medical equivalent of a perfect storm. In response to a still-unknown trigger, some people mount an aggressive immune response against the insulin-secreting β cells of the pancreas. Usually striking in childhood, this autoimmune assault destroys its victims' ability to regulate their blood sugar levels. The pancreas is a particularly unfortunate target for such an attack, as it has essentially no ability to regenerate itself. Once the β cells are gone, they don't come back, and the disease's long-term sequellae can range from limb loss to coma to death.
The pancreas grows from stem cells during embryo development, so with the right type of stem cells and the right environment, it should be possible to regenerate the beleaguered pancreas of a type 1 diabetes patient.
Diverse approaches to regenerating β cells
Before delving into current research, Allen Spiegel (Albert Einstein College of Medicine) began with a brief history of diabetes therapy. The original treatment for the disease was starvation, which prevents diabetic crisis but has the unfortunate side effect of killing the patient. Insulin therapy, developed by Frederick Banting in 1922, revolutionized diabetes treatment but still failed to cure the disease.
Attacking a problem he describes as "harder than rocket science," Spiegel and his colleagues are searching for ways to stimulate the regeneration of β cells. So far, the team has found at least three promising strategies. First, precursor cells in the pancreas can exhibit β cell-like insulin responses under the right conditions, so it might be possible to stimulate the precursor cells to replace the missing β cells functionally. Second, Spiegel suggests that specific immunosuppression could help preserve remaining β cells before the patient's immune system has a chance to eradicate them. Third, the scientists have discovered that in mice, disrupting a single gene, called Men1, can lead to pancreatic cell proliferation. If that finding holds true in humans, MEN1-targeting drugs or gene therapy might help regenerate the pancreas.
Gordon Keller (Mount Sinai School of Medicine) put the subject into embryological context. The pancreas normally grows from the embryonic endoderm, a tissue produced during gastrulation, or formation of the gut. Keller and his colleagues hope to approximate gastrulation in vitro to generate pancreatic cells.
With careful manipulation, embryonic stem cells can yield pancreas-like cells.
Under the right conditions, mouse embryonic stem cells will form "embryoid bodies" in culture dishes, and the researchers used this system to identify some of the signaling pathways required for gastrulation. With careful manipulation, the cultures can yield hepatocytes, as well as some pancreatic-like cells on the margins of the hepatocyte colonies. Encouragingly, the cultured hepatocytes can occasionally become functional liver cells when transplanted into animals. The team is now testing the process in human stem cell lines.
Domenico Accili (Columbia University) shifted the focus to the concerns of diabetes patients, many of whom were in the audience. Insulin therapy was a definitive medical breakthrough, turning a death sentence into a manageable disease. Accili says that while stem cells have substantial promise, patients should not expect another giant leap anytime soon.
Reviewing recent advances like the Edmonton protocol for pancreatic cell transplantation, and efforts to generate β cells in vitro, he concludes that there is no way to predict which, if any, of the current crop of projects will yield treatments. That's a good reason to avoid premature optimism, but also a good reason to pursue further research.
Development and redevelopment of the pancreas
Doug Melton (Harvard University) departed from the broad generalities of a typical keynote presentation to delve directly into new data. In his laboratory's type 1 diabetes work, the focus is on how solid organs, especially the pancreas, regulate their development.
The team uses mice lacking the Pdx1 gene as their primary model system. The developing pancreas normally expresses Pdx1, and animals without functional Pdx1 lack pancreases. Injecting wild-type embryonic stem cells into these mice causes them to grow pancreases, but the size of the organ depends on the number of injected cells. That suggests that the pancreas has an intrinsic size limit determined by the number of starting cells.
The number of starting stem cells may determine pancreas size.
Reversing the experiment, the scientists generated a mouse strain in which the Pdx1 promoter drives an inducible toxin gene system. Feeding a chemical inducer to these mice kills any developing pancreatic cells, but does not kill fully developed pancreatic cells. If pregnant mice receive the inducer when their embryos are between 9 and 10 days old, the resulting pups have underdeveloped pancreases. Feeding the inducer at day 11 or later has no effect on the organ's size, suggesting that once the pancreas is developed, it no longer contains any stem cells that could regenerate the organ.
Searching for ways to stimulate pancreatic regeneration that do not require preexisting pancreatic stem cells, Melton and his colleagues are now using "high-throughput screening," a procedure common in the pharmaceutical industry but rare in basic research. After adapting the technology to their unique experimental system, the team is now screening thousands of genes in embryonic stem cells to find those that induce pancreatic growth during development.
While it will likely be years before the work leads to usable treatments, Melton is optimistic. "We haven't learned anything that leads us to believe that this is not a solvable problem," he says.
John Gearhart, Johns Hopkins University
Kenneth Chien, Harvard Medical School
Warren Sherman, Columbia University
Amit Patel, University of Pittsburgh
A heart-fixing job of staggering complexity
Our minds tell us, perhaps a bit self-servingly, that the most important organ in the body is the brain. Nonetheless, humans have realized for millennia that the hardworking, essential, and fragile heart also deserves special treatment. Serious brain damage can be debilitating, but serious heart damage is instantly lethal.
The heart has a formidable capacity to repair itself.
Considering its pedestrian function—it's just a pump, after all—the heart has proven surprisingly difficult to repair, and virtually impossible to replace. When coronary arteries clog, radiologists can scrape them out and surgeons can bypass them, but the long-term damage from lost blood flow, or ischemia, often persists. Meanwhile, engineers have designed hundreds of ingenious heart prosthetics, from pacemakers to replacement valves to artificial hearts, but their uses are still limited by infections and immune responses, as well as the malfunctions and ordinary wear that affect all machines.
Fortunately, the heart has a formidable capacity to repair itself, if the patient can be kept alive long enough. Researchers attempting to speed the heart's healing have long hoped that stem cells would be the answer, and the early results have been tantalizing. When scientists remove exogenous growth factors and leave cultured embryonic stem cells to their own devices, the petri dish soon grows different types of embryonic tissue, including cardiomyocytes that start pulsating spontaneously.
A beating cluster of cells is a long way from a replacement heart, but the gap between the laboratory and the clinic seems to be narrowing.
Purifying cardiac stem cells for treatment of heart disease
Reviewing the literature on stem cells in heart disease, John Gearhart (Johns Hopkins University) found more than 40 studies in which scientists had used stem cells to repair heart damage in patients. In every study, the stem cells improved heart function at least somewhat, even though the experimental designs, conditions, outcome measures, and stem cell sources were different in each study. Everything seems to work a little bit. While that's encouraging, it provides few clues to the underlying mechanisms of cardiac regeneration.
"All of these different cell sources have been used, [so] when you actually then look at the outcome measures, you don't really know what this improvement is due to," says Gearhart.
A new line of heart stem cells can yield working heart cells.
One major problem is that the stem cells the patients have received have been mixed populations, with multiple cell types that could be contributing to the outcome. To get around that, Gearhart and his colleagues went back to tissue culture, and created an embryonic stem cell line in which a cardiac-specific gene promoter drives a green fluorescent protein (GFP) gene. GFP glows green under ultraviolet light, so as the stem cells differentiated, the investigators could separate them with a cell sorter and isolate only the cardiac cells. Testing these, they purified a line of heart stem cells that can regenerate themselves and also give rise to working heart cells.
In a mouse model of cardiac infarction, grafting the newly isolated stem cells into the heart improves cardiac output. The researchers are now testing the new cell line in the clinic, and also trying to characterize the genes involved in cardiomyocyte differentiation.
Lineage analysis of cardiac cells
Kenneth Chien (Harvard Medical School) and his colleagues are also searching for heart stem cells, by tracing cell lineages in developing mouse hearts. Chien reasoned that if the heart is like the blood, in which all cell types come from a single type of progenitor cell, then tracing heart cell lineages should lead directly to a cardiac stem cell. He was right.
To make a heart, a developing embryo has to direct the formation of three types of tissues: endothelium, smooth muscle, and cardiac muscle. "In other words there's a branch point, where sometime in development in the embryo ... this decision is made," says Chien. Cells that are committed to being cardiac tissue, but have not decided what specific cell type they will form, could be clinically useful cardiac stem cells.
Tracing the lineages of murine heart cells during development, the investigators found that a protein marker called Islet-1 flags exactly the cells they were seeking. "Smooth muscle cells, endothelial cells, and conduction system cells ... are actually derived from Islet precursors, so at some point in time Islet is the common denominator for all these lineages," says Chien.
Can bone marrow-derived stem cells work in the heart?
The session also featured comments from two sides of an ongoing controversy, in response to a pair of articles published two weeks earlier. In the articles, different teams of researchers described the results of treating heart disease with adult bone marrow-derived stem cells. One team saw positive results, the other negative, and surgeons and stem cell scientists are now lining up on both sides of the issue. Chien emphasized the negative results, saying that the apparent failure of adult stem cells in this application highlights the need for further research on embryonic stem cells.
Warren Sherman (Columbia University), who spoke after Chien, thinks otherwise. "The story is not over in my opinion, and I think it would be a mistake for us to abandon any initial effort ... prematurely," says Sherman, a surgeon who specializes in post-ischemic heart disease.
Post-ischemic disease, a common condition within the umbrella category of "heart disease," is what happens after a patient loses blood flow to a portion of the heart. In recent years, surgeons have tried to heal post-ischemic disease by injecting the affected areas of the heart with stem cells from various sources, including bone marrow-derived, adipose-derived, and fetal cells. The theory is that the right type of stem cells will differentiate into cardiac muscle to repair the post-ischemic damage, but the results have been ambiguous. The controversial pair of recent papers was a continuation of this strategy, using a subpopulation of bone marrow-derived stem cells expressing the CD34 protein. Those cells had looked promising in preclinical studies, but the clinical results were less impressive.
However, the lackluster results in humans could be a product of the trial design. In the earlier preclinical studies, researchers induced myocardial infarctions in rats, then injected more than 3000 stem cells per gram of tissue into the animals' hearts. In the human trials, patients received a much smaller dose of cells relative to the amount of heart tissue. "At best, when we translated [these] preclinical data into the clinical domain, we fell at least a power of ten short in terms of what might work," says Sherman.
Amit Patel (University of Pittsburgh) also believes that adult stem cells are a promising tool for treating heart disease, and points out that they have some advantages over embryonic or fetal cells. For example, adult cells can be derived from the patient, eliminating the risk of an immune response against the injected cells. "No matter how positive the potential outcomes are, we still have to deal with our own immune systems," says Patel.
To avoid that problem, Patel and his colleagues took bone marrow from patients undergoing heart bypass surgery, quickly isolated stem cells, and sent the cells back to the operating room. With the patient still on the table, surgeons then injected the cells into the ischemic areas of the heart that they were unable to repair with bypasses. By several measures, patients who received this treatment fared better than controls who received only the bypass operation.
The researchers are testing similar autologous stem cell strategies in patients with other types of heart disease, and while the results are promising, Patel cautions that the strategy is not a panacea. "For every 100 patients that get screened for one of these trials, 5% qualify," he says, adding that "this is not something that's just globally applicable to all patients."
The panel discussion at the end of the session echoed Patel's cautionary tone. In other words, while the potential of cardiac stem cells is heartwarming, we should be careful not to lose our heads.
Shahin Rafii, Weill-Cornell Medical College
Konrad Hochedlinger, Harvard Medical School
Elaine Fuchs, The Rockefeller University
From regression to remission
During development, the cells in an embryo carry out a long series of rapid, carefully controlled divisions and specializations. A fertilized egg divides into two cells, then four, then eight, and so on, each cell retaining the potential to create all of the tissues in an adult. These are totipotent stem cells.
As a tumor grows, oncology recapitulates ontogeny.
As development proceeds, the dividing cells progressively narrow their options, first committing to form general tissue types, then specific subtypes. In the process, they lose their totipotency. At birth, most of an individual's cells have become terminally differentiated, ready to serve out their hyperspecialized lives before being replaced by duplicates.
In cancer, the process partially reverses. Rather than succumb to its proper fate, a differentiated cell divides, generating a tumor. As the tumor grows, it often regains hallmarks of embryonic tissue; oncology recapitulates ontogeny. That makes cancer doubly interesting to biomedical researchers: as a disease in need of new treatments, and as a model system for studying the behavior of stem cells.
Rebuilding the vasculature
Shahin Rafii (Weill-Cornell Medical College) discussed his work on one of the hottest topics in cancer research: angiogenesis, or the development of new blood vessels. When a tumor grows larger than a few millimeters in diameter, it must recruit its own blood supply, or the interior cells will die. While oncologists want to stop angiogenesis, clinicians using stem cell-based therapies will need to start it—both need more information about how the process works.
"If the vascular system is not reconstructed, none of the translational stem cell therapy is going to work," says Rafii, adding that no matter how many stem cells researchers transplant into a patient, "if there [are] no stabilized vessels, that newly formed tissue is going to collapse."
To stabilize newly generated blood vessels, a developing organ, stem cell transplant, or tumor needs to recruit perivascular cells to surround and support the vessels. By culturing a population of human fetal liver cells with appropriate growth factors, Rafii and his colleagues managed to replicate this process, training the cells to form stable vascularized tissue when transplanted into the ear of an immunocompromised mouse. Using similar techniques, the team has also produced functional, vascularized heart muscle tissue from human embryonic stem cells.
The investigators also found that blocking the growth of endothelium prevents muscle tissue growth, underscoring Rafii's argument that angiogenesis is essential for tissue or organ regeneration. The researchers are now searching for the specific molecular signals that coordinate tissue growth with blood vessel stabilization.
Stimulating proper differentiation of stem cells
Konrad Hochedlinger (Harvard Medical School) explained how he uses cancer as a model system for studying stem cell biology. For most types of stem cell therapies to work, researchers need to be able to reprogram the nucleus of a partially or fully differentiated cell, turning back the developmental clock to the time when the cell was pluripotent. Currently, cells can be reprogrammed in the laboratory with a handful of techniques, including somatic cell nuclear transfer, explantation of the cells from live tissue into tissue culture, and fusion of somatic cells with established embryonic stem cell lines. Each approach has its own serious drawbacks, and none works reliably.
Oct-4 and Cdx-2 are two of the factors regulating reprogramming.
A better strategy would be to reprogram the cells by exposing them to specific transcription factors, something tumors do routinely. To find out how, Hochedlinger and his colleagues started with a short list of factors that can stimulate cultured fibroblasts to adopt a stem cell-like phenotype. The researchers created a transgenic mouse in which they could induce the expression of one of these factors, called Oct-4, at any time.
Inducing Oct-4 expression in a mouse appears to stimulate existing stem cells to proliferate, while inhibiting cell differentiation, causing tumors in the animal's gut and skin. Oct-4 expression is inversely proportional to the expression of another factor, Cdx-2. Knocking down Cdx-2 expression with inhibitory RNA during embryonic development also causes tumors in the intestine, but inhibiting Cdx-2 in adult animals has no effect, so the gene is only required for cell programming in a specific period of development. The scientists are now using their mouse systems to pinpoint additional factors that control reprogramming.
Elaine Fuchs (The Rockefeller University) concluded the session with a brisk presentation that got under the skin—which, it turns out, is an excellent place to study both stem cells and cancer. Skin cancer is the most prevalent type of cancer, and skin itself is "a readily accessible tissue, its lineages are spatially and temporally defined," Fuchs explained. "Adult skin stem cells ... are in fact able to propagate in culture, and they do have clinical potential."
In mammals, the descendants of stem cells in the lowest layer of the skin specialize as they move to the surface, forming the protective barrier of the epidermis as well as more complex structures, such as sweat glands and hair follicles. The Wnt signaling pathway regulates this process; mice with a disrupted Wnt pathway become inordinately furry, and also develop hairball-like skin tumors called pilotricomas.
Looking at downstream targets and effects of Wnt, Fuchs and her colleagues are now identifying the signals responsible for switching skin cells onto specific developmental tracks. "We're beginning to understand the earliest processes by which multipotent cells commit to taking one path or another path," says Fuchs. The researchers hope to use that understanding to develop skin grafts with hair follicles and sweat glands, which current grafts lack.
Some of the underlying processes in skin cell programming are broadly conserved across different species and cell types, so learning how to reprogram skin stem cells could illuminate ways to reprogram other cell types. Skin, it seems, is more than skin deep.
Lorenz Studer, Memorial Sloan-Kettering Cancer Center
Hynek Wichterle, Columbia University
Hongjun Song, Johns Hopkins University
Arnold Kriegstein, University of California, San Francisco
Neurology is the poster child of stem cell research. The promise of treating conditions like paralysis, amyotrophic lateral sclerosis, and Parkinson's disease prompts celebrities to testify before Congress, medical activists to organize lobbying campaigns, and companies to build entire research facilities.
Even the embryonic stem cells themselves seem to favor neurological applications. "For peculiar and curious reasons, stem cells have a predeliction to undergo pathways of neural differentiation," explains Thomas Jessell, who chaired the session on neurology.
Stem cells like to become neurons.
Better still, some neuronal cells maintain their multipotency all the way into adulthood, holding out the promise that researchers might be able to dodge the ethical and immunological challenges of using embryonic cells. "In the nervous system ... it's become progressively more established that there are adult neural stem cells in certain privileged areas," says Jessell.
But that's where the good news ends. To turn laboratory findings into clinical treatments, researchers need to produce specific kinds of cells, and there are dozens of types to choose from in the brain. Reversing paralysis may call for new motor neurons, while curing Parkinson's disease will take dopaminergic neurons. They are not interchangeable.
Best practices for stem cell generation
Researchers are taking numerous parallel approaches, ranging from advanced preclinical studies of specific treatments to basic research on brain development, to address the need for specific neural cells.
Lorenz Studer (Memorial Sloan-Kettering Cancer Center) wants to use embryonic stem cells to treat Parkinson's disease. As a starting point for this ambitious project, he asked a simple question: How well do the available embryonic stem cell lines grow in culture? Comparing 8 lines that are approved for NIH-funded research and 14 lines derived after August 2001 (and therefore not approved), they found substantial differences in growth rates. That wasn't so surprising, but the data revealed something else that was.
"We would have thought maybe these growth rates related to [the] stochastic genetic makeup of the cells," says Studer, but "growth rates correlate not with stochastic variability but ... the lab that they were derived from." Some labs apparently derive better stem cells than others, and so far, nobody knows why.
In response, Studer and his colleagues are borrowing a technique from the drug industry, screening thousands of cell lines with different potential signaling molecules to see what factors are required for stem cell maintenance and growth.
Besides this "high-throughput screening" approach, the team is also implanting stem cell-derived dopaminergic neurons into the brains of rats with Parkinson's disease. The implanted cells appear to survive and multiply, and while they prompt some overgrowth of neurons, the researchers are optimistic that the approach could work in humans. "We are still a way from using these cells in a clinical setting, but we've made a lot of progress," says Studer.
From embryonic stem cell to motor neuron
Hynek Wichterle (Columbia University) and his colleagues are trying to generate motor neurons from embryonic stem cells. The loss of motor neurons is a hallmark of deadly and currently incurable diseases like amyotrophic lateral sclerosis and spinal muscular atrophy, but replacing these specialized neurons is a challenge. "We can ... relatively easily generate neurons from embryonic stem cells, but to go to very particular and specific subtypes of neurons can be quite tricky," says Wichterle.
To figure out how to do it, the researchers used embryonic stem cells from mice that carry a green fluorescent protein gene. Because the cells glow under ultraviolet light, they are easy to trace as they develop. Exposing the mouse cells to fibroblast growth factor and retinoic acid prompted them to differentiate into motor neurons, which were functional when transplanted into chicken embryos.
Importantly, the team also found that they could produce motor neurons adapted for more anterior or more posterior portions of the developing spinal cord, by manipulating the concentrations of retinoic acid and fibroblast growth factor. They are now using the cultured motor neurons as a model system to study nervous system development and disease.
Encouraging adult neural stem cell growth in vivo
Hongjun Song (Johns Hopkins University) noted that, "It actually took about 100 years for people to appreciate that our brains are not static, and we do have some neurons that are generated in specific regions," referring to the cells of the subventricular zone and the dentate gyrus, which sometimes can regenerate.
Outside these two specific regions, though, cell division does not normally produce new neurons, and Song and his colleagues want to know why. The researchers derived multipotent neuronal stem cells from adult rat brains, and from human brain samples taken during surgeries. These stem cells can grow new neurons in tissue culture. In rats, the cultured stem cells can grow and apparently form new synapses when transplanted into the hippocampus of the brain, but not when put into the spinal cord. Specific promoter and inhibitor signals in neuronal compartments seem to drive this bias.
Birth and development of neurons in the cerebral cortex
Arnold Kriegstein's group (University of California, San Francisco) focuses on the role of neural stem cells in the development of the cerebral cortex. Much of Kriegstein's work focuses on radial glial cells, which were thought to serve merely as a scaffolding system in the developing brain; radial glial cells grow long processes, which neurons then migrate along to reach their final destinations.
Radial glial cells are the mothers and architects of the cerebrum.
In order to track this migration, the researchers injected the radial glial cells of developing mice with a retrovirus carrying a green fluorescent protein gene. The injected cells and their descendants then glow under ultraviolet light. That's when the team got a surprise. "In fact, the radial glial cell gives rise to the neuron, and then in a sense guides the neuron to the cortex, because it migrates along the parental fiber to get to its final position," says Kriegstein.
New neurons bud from the base of the radial glial cell, then migrate along the mother cell's extended body, stacking into their final positions like cars reaching the end of a one-lane road. By changing the types of neurons they spawn at different times during development, the radial glial cells may orchestrate the formation of distinct layers in the finished brain. Rather than being mere scaffolding, the radial glial cells are both the mothers and the architects of the deep cerebral cortex.
Kriegstein suggests that a few relatively simple genetic changes in this developmental program could explain the evolution of more heavily folded cerebral cortexes, which are essential for higher reasoning. If that's correct, then radial glial cells are more than just an interesting research subject. They literally make you think.
Somatic Cell Nuclear Transfer
What molecular signals stimulate human eggs to begin blastocyst formation?
Can existing stem cell lines be weaned from their dependence on feeder cells?
Why is so much mRNA destroyed in the first three days of embryonic development?
Do stem cell-derived neurons mimic the pathogenesis of ALS accurately?
Diabetes and Autoimmune Disease
What are the genes that induce pancreatic growth during development, and can they be activated in adults with type 1 diabetes?
Will stem cells ultimately yield a breakthrough analogous to Banting's invention of insulin therapy?
Can pancreatic cells derived in tissue culture survive and function in adult animals?
What is the normal role of the Men1 gene in stimulating pancreatic development?
Can Islet-1-derived stem cells yield functional new heart tissue in patients?
Is adult bone marrow a realistic source for heart stem cells?
Will autologous stem cell transplants be as useful in the general heart patient population as they appear to be in specific subsets of patients?
What are the molecular signals that coordinate tissue growth with angiogenesis?
Besides Oct-4 and Cdx-2, what other factors regulate stem cell reprogramming in development?
What are the signals downstream of Wnt that switch skin cells onto specific developmental tracks?
Will implanted dopaminergic neurons survive and function in the brains of Parkinson's disease patients?
Can stem cell-derived motor neurons function in adult mammals?
What are the signals directing the growth of new neurons from the stem cells naturally present in the adult brain?
Can a few simple mutations explain the evolution of higher reasoning?